JP2007184818A - Audio apparatus, sound reproducing method, and sound reproducing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a listener who is not on an axis of symmetry in the middle between right and left speakers to perceive a surround sound from the rear and a spread by using a front surround system. <P>SOLUTION: Main signal generating circuits 34L and 34R generate main signals SLm and SRm wherein transfer characteristics from an array speaker system SPAr to a listening area are canceled and transfer characteristics from the rear to the listening area are convolved from audio signals SL and SR of rear channels, and auxiliary signal generating circuits 35L and 35R generate opposite-phase signals from the main signals SLm and SRm and also generate auxiliary signals SLa and SRa by delaying phases of at least the opposite-phase signals. A sound field composite signal generating circuit 36 generates a plane wave from the auxiliary signals SLa and SRa and supplies it to the array speaker system SPAr. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus, method, and program capable of forming a wide listening area when reproducing an audio signal having a rear channel such as a 5.1 channel surround sound signal.

  Home theater systems using large screen displays and 5.1 channel surround speaker systems have come to be used. Here, the 5.1 channel surround speaker system has a left channel (Lch) speaker, a center channel (Cch) speaker, a right channel (Rch) speaker, and a rear channel of the viewer arranged in front of the viewer. It has six audio channels, a surround left channel (SLch) speaker, a surround right channel (SRch) speaker, and a subwoofer channel (Wch) speaker, and can form a realistic reproduction sound field. It is.

  That is, “5” of 5.1 channel means three front speakers and two surround speakers (rear speakers), and “.1” means a subwoofer channel that compensates for low frequency components. Recently, a surround speaker system having a larger number of channels such as a 7.1-channel surround speaker system has been provided.

  Provided by being recorded on a DVD (Digital Versatile Disc), for example, using a home theater system equipped with a so-called front surround speaker system that also outputs a rear channel audio signal through a speaker arranged only in front of the listener When viewing and listening to 5.1 channel audio compatible movie content, the viewing position (listening position) where the most realistic sound can be heard is placed in front of the listener. Only on the axis of symmetry between the left channel (Lch) speaker and the right channel (Rch) speaker, that is, at a position equidistant from both the left channel (Lch) speaker and the right channel (Rch) speaker. is there.

  Of course, the home theater system may be used by one person, but may be used by a plurality of persons such as the whole family. However, as described above, it is only one listener located on the symmetry axis of the left and right speakers that can hear the sound with the most realistic feeling, and for the listeners around it. It is considered that there are cases where it is impossible to effectively listen to a sound with a sense of presence.

  Therefore, Patent Document 1 discloses a technique for a so-called front surround speaker system, in which a listener at the center position of the left and right speakers and a total of three listeners on both sides thereof are connected to the ears of the listeners. A technique is disclosed in which three people perceive a sense of backward localization by correcting a transfer function and adjusting a time axis by a delay. By using the technique described in Patent Document 1, it is possible to form a reproduction sound field in which three listeners can simultaneously listen to realistic sounds.

The above-described Patent Document 1 is as follows.
Japanese Patent Laid-Open No. 05-244697

  By the way, without using a surround speaker that should be placed behind the listener, the same transmission characteristics as the sound that arrives from the back to the ear are reproduced with a frontal speaker, using transoral technology. For example, a speaker system using a front surround system such as the technique described in Patent Document 1 that forms a certain reproduced sound field has been widely used.

  However, in the case of the technique disclosed in Patent Document 1 described above, since the rear localization is perceived by correcting the transfer function up to the listener's ear, if the listening position of each of the three persons deviates from the assumed listening position, the receiving is performed. There is a problem that an error occurs in the waveform of the audio signal generated in the ear of the listener and the rear localization is not perceived. In addition, there are individual differences in the transfer function of the sound to the listener's ears, and even if the listening position is assumed by the system, the rear localization may not be perceived by the listener due to the effects of individual differences. There is a problem.

  In general, when transoral technology is used, it is not always possible to obtain a clear rear sound image because of two errors, namely, the effect of individual differences in transfer characteristics and the effect of errors in transfer characteristics due to deviation in listening position. Not exclusively. In other words, even if you can get a sense of localization to the rear, you can only get a vague sense of sounding from the side or the back, and you can't get a clear sound image localization that is usually said. .

  In view of the above, this invention makes it possible for a listener to perceive surround sound and a sense of spread from behind without having to be on the symmetry axis in the middle of the left and right speakers. It is an object of the present invention to provide a front-surround sound device that enables everyone to obtain a surround sound and a feeling of spread from the rear even when enjoying a movie on a large-screen television, for example.

In order to solve the above problem, an audio device according to claim 1 is provided.
A front surround type sound device that reproduces a surround sound source having a rear channel that is a channel of a rear surround sound through a speaker group including a plurality of speakers arranged adjacent to only in front of a listener,
Based on the rear channel signal, a main signal generating means for generating a main signal that cancels the transfer characteristic from the speaker group to the listening area and convolves the transfer characteristic from the rear to the listening area;
Auxiliary signal generating means for forming an antiphase signal from the same signal as the main signal and generating an auxiliary signal at least delayed in phase of the antiphase signal;
An audio signal supplied to the loudspeaker group, which is a main signal for forming a sound signal for a main signal radiated as a plane wave from a direction opposite to the left and right to the listening area from the auxiliary signal. Sound signal generating means,
Auxiliary signal that is an audio signal of audio radiated from the group of speakers, and that forms a sound signal from the auxiliary signal for an auxiliary signal radiated as a plane wave from the opposite direction to the main signal toward the listening area. And a sound case signal generating means.

  According to the acoustic apparatus of the first aspect of the present invention having such a configuration, the spectral envelope of the transfer characteristic to be rearranged is transmitted to the listener's ear, and the main signal and the auxiliary signal interfere with each other in the listening area. As a result, the interaural difference is different from the interaural difference produced by the sound wave coming from the front, and the transfer characteristic for rearward localization is emphasized psychologically, so that the sound image can be perceived backward. In addition, since the sound is reproduced as a plane wave through a speaker group including a plurality of speakers, the reproduced sound can be satisfactorily heard over a wider range.

  According to the present invention, when a rear surround signal created on the assumption that it is presented from the rear is reproduced from a front speaker installed in front of the listener, transfer characteristics serving as a clue to rear sound image perception are displayed in the listening area. The main signal to be reproduced is radiated as a plane wave, and an auxiliary signal that causes interference between the main signal and the listening area and emphasizes the backward sound image perception cues is radiated as a plane wave, so it is heard in the middle of the listening area. Even without this, it is possible to enjoy surround sound having a rear channel only with a speaker installed in front.

  Hereinafter, an embodiment of an apparatus and a method according to the present invention will be described with reference to the drawings. In the embodiments described below, the apparatus, method, and program according to the present invention will be described by taking as an example the case where the present invention is applied to an optical disk playback device such as a DVD (Digital Versatile Disc) on which video data and audio data are recorded. To do.

[Configuration and operation of playback device]
FIG. 1 is a block diagram for explaining the reproducing apparatus of this embodiment. As shown in FIG. 1, the playback apparatus of this embodiment includes an optical disk reading unit 1, a demultiplexing circuit 2, an audio data processing system 3, and a video data processing system 4. The audio data processing system 3 includes an audio data decoder 31, a time axis adjustment circuit 32, amplification circuits 33W and 33F, a subwoofer channel speaker SPW, a left channel speaker SPL, a center channel speaker SPC, a right channel speaker SPR, and a main signal generation. Circuits 34L, 34R, auxiliary signal generation circuits 35L, 35R, sound field signal generation circuits 36 (1), 36 (2), 36 (3), 36 (4), mixer 37, n-channel amplification circuit 38, array speaker system The video data processing system 4 includes a subtitle data decoder 41, a subtitle playback circuit 42, a video data decoder 43, a video playback circuit 44, a superimpose circuit 45, and a video display device 46.

  Although not shown, the optical disk reading unit 1 is an optical pickup including an optical disk loading unit, an optical disk rotation drive unit including a spindle motor, an optical system such as a laser light source, an objective lens, a biaxial actuator, a beam splitter, and a photodetector. And a sled motor for moving the optical pickup unit in the radial direction of the optical disc, various servo circuits, and the like.

  Then, the optical disk reading unit 1 irradiates the optical disk loaded therein with a laser beam and receives the reflected light, whereby video data, subtitle data, and multi-channel audio data recorded on the optical disk are received. The multiplexed data in which various other data are multiplexed is read out, and necessary processing such as error correction is performed, and this is supplied to the demultiplexing circuit 2.

  In this embodiment, each of the video data, caption data, and multi-channel audio data recorded on the optical disk loaded in the optical disk reading unit 1 is data-compressed by a predetermined encoding method. is there.

  In addition, multi-channel audio data recorded and provided on an optical disc includes 2-channel intensity stereo audio data, 5.1-channel so-called multi-channel audio data, 7.1-channel multi-channel audio data, etc. Although there are various types, this embodiment will be described as 5.1 channel so-called multi-channel audio data.

  The demultiplexing circuit 2 separates video data, caption data, 5.1 channel audio data, and other various data from the multiplexed data supplied thereto. Then, the demultiplexing circuit 2 supplies the separated left and right two-channel audio data to the audio data decoding unit 31 of the audio data processing system 3, and the separated subtitle data is supplied to the subtitle data decoder 41 of the video data processing system 4. The separated video data is supplied to the video data decoder 43 of the video data processing system. Other data is supplied to a control unit (not shown) and used for various controls.

  The caption data decoder 41 of the video data processing system 4 performs compression / decompression processing or the like on the caption data supplied thereto, restores the original caption data before data compression, and supplies this to the caption reproduction circuit 42. . The caption reproduction circuit 42 performs necessary processing such as D / A (Digital / Analog) conversion processing for converting the compressed and decompressed caption data supplied thereto into an analog signal, and generates a caption signal to be synthesized with the video signal. This is formed and supplied to the superimpose circuit 45.

  The video data decoder 43 of the video data processing system 4 performs compression / decompression processing or the like on the video data supplied thereto to restore the original video data before data compression, and sends this to the video playback circuit 44. Supply. The video reproduction circuit 44 performs necessary processing such as D / A (Digital / Analog) conversion processing for converting the compressed and decompressed video data supplied thereto into an analog signal, and reproduces the video signal. Is supplied to the superimposing circuit 45.

  The superimpose circuit 45 performs a predetermined process for synthesizing the subtitle signal with the video signal supplied thereto, forms a video signal for synthesizing the subtitle, and supplies the video signal to the video display device 46. Supply. The video display device 46 is provided with a display element such as a liquid crystal display (LCD), a plasma display panel (PDP), an organic electroluminescence (EL) display, a cathode ray tube (CRT), and the like. A video corresponding to the video signal from the pause circuit 45 is displayed on the display screen of the display element.

  In this way, the video corresponding to the video data and subtitle data read from the optical disc is displayed on the display screen of the video display device. In this embodiment, the playback device itself has been described as including a video display device, but the present invention is not limited to this. The reproduction video signal from the superimpose circuit 45 can be supplied to a monitor receiver provided outside, and the reproduction video signal from the superimpose circuit 45 is converted into a digital signal. A / D (Analog / Digital) conversion processing may be performed and digital output may be performed.

  On the other hand, the audio data decoder 31 of the audio data processing system 3 performs compression / decompression processing or the like on each of the 5.1 channel audio data supplied thereto to restore the original audio data before data compression. The restored subwoofer channel audio signal W, left channel audio signal L, center channel audio signal C, and right channel audio signal R are supplied to the time axis adjustment circuit 32, and The audio signal SL of the surround left channel (left rear channel) is supplied to the main signal generation circuit 34L and the auxiliary signal generation circuit 35L, and the audio signal SR of the surround right channel (right rear channel) is supplied to the main signal generation circuit 34R and the auxiliary signal generation circuit 34L. The signal is supplied to the signal generation circuit 35R.

  The time axis correction circuit 32 performs delay processing on the audio signals W of the subwoofer channel, the audio signal L of the left channel, the audio signal C of the center channel, and the audio signal R of the right channel supplied thereto. To correct the time axis. In the time axis correction circuit 32, the time-domain corrected subwoofer channel audio signal W is supplied to the subwoofer channel speaker SPW through the amplifier circuit 33W.

  The left channel audio signal L, the center channel audio signal C, and the right channel audio signal R are supplied to the front speaker through the amplifier circuit 33F. The amplifier circuit 33F can amplify each of the left channel audio signal L, the center channel audio signal C, and the right channel audio signal R. The front speaker includes a left channel speaker SPL, a center channel speaker SPC, and a right channel speaker SPR.

  Thereby, the sound corresponding to the audio signal W of the subwoofer channel is emitted from the subwoofer channel speaker SPW. The left channel speaker SPL, center speaker SPC, and right channel speaker emit sound corresponding to the left channel audio signal L, the center channel audio signal C, and the right channel audio signal R.

  In this specification, the left channel speaker SPL, the center speaker SPC, and the right channel speaker are usually installed in front of the listener and are therefore called front speakers. The subwoofer channel speaker SPW can be installed at various positions in relation to the listener, but is included in the front speaker for convenience in order to distinguish it from the surround speaker installed behind the listener. To think. Therefore, in this specification, unless otherwise specified, the term “front speaker” refers to the left channel speaker SPL, the center speaker SPC, the right channel speaker, and the subwoofer channel speaker SPW.

  The playback apparatus of this embodiment is listened to so that the listener receives the surround left channel audio signal SL to be heard so as to come from the left rear of the listener and the right rear of the listener. The sound signal SR of the surround right channel to be applied is a single speaker group formed by arranging a plurality of speakers arranged in front of the listener in a horizontal row by applying a wavefront synthesis technique for the audio signal. The sound is emitted from a so-called array speaker system SPAr.

  Note that, as described above, the surround left channel audio signal is an audio signal of a channel to be heard so as to come from the left rear of the listener, and the rear left channel audio signal or the left rear channel audio It is also called a signal. Further, as described above, the surround right channel audio signal is the audio signal of the channel that should be heard so as to come from the right rear of the listener, and the rear right channel audio signal or the right rear channel audio. It is also called a signal.

  In this embodiment, the array speaker system SPAr is a group of speakers formed by arranging a plurality of speakers in a horizontal row as described above. In this embodiment, adjacent speakers are arranged. 16 speakers with a distance between the centers of 10 cm (centimeters), for example, are arranged side by side.

  As described above, in the playback apparatus of this embodiment, the surround left channel (left rear) is arranged from the array speaker system SPAr arranged in front of the listener without arranging a physical surround speaker in the rear of the listener. Sound corresponding to the sound signal SL of the channel) and sound corresponding to the sound signal SR of the surround right channel (right rear channel), and these sounds are heard as if they are coming from behind the listener. By making it possible to listen as described above, it is possible to form a realistic reproduction sound field.

  As will be described in detail later, the main signal generation circuit 34L that receives the supply of the surround left channel audio signal SL cancels the transfer characteristics of the audio signal SL when a plane wave arrives from the left front to the left ear. Thus, the main signal SLm that enables the transfer characteristic from the left rear to the left ear to be reproduced in the left ear is formed from the surround left channel audio signal SL, and this is supplied to the sound case signal generator 36 (4). .

  Further, in the auxiliary signal generation circuit 35L that receives the audio signal SL of the surround left channel, the same signal as the main signal SLm formed in the main signal generation circuit 34L is phase-inverted, and this phase-inverted signal (main The auxiliary signal SLa that interferes with the main signal SLm in the listening area is generated by delaying at least the phase of the signal SLm), and this is supplied to the sound signal generation signal generation circuit 36 (3). In the generation of the auxiliary signal SLa, not only the phase is delayed but also the phase may be delayed and the amplitude may be attenuated.

  In this way, the main signal generation circuit 34L and the auxiliary signal generation circuit 35L are formed from the surround left channel audio signal SL in order to form an audio signal for localizing the sound image to the left rear of the listener. Then, processing is performed to generate signals that have opposite phases and that have adjusted transfer characteristics (frequency characteristics).

  Similarly, in the main signal generation circuit 34R that receives the supply of the surround right channel audio signal SR, the transfer characteristic when a plane wave arrives from the right front to the right ear is canceled for the listener, and the right rear to the right A main signal SRm that enables reproduction of the transfer characteristic to the ear to the right ear is formed from the sound signal SR of the surround right channel, and this is supplied to the sound case signal generation circuit 36 (2).

  Further, in the auxiliary signal generation circuit 35R which receives the supply of the surround right channel audio signal SR, at least the same signal as the main signal SRm formed in the main signal generation circuit 34L is phase-inverted, and this phase-inverted signal ( In the listening area, the auxiliary signal SRa that interferes with the main signal SRm is generated by delaying at least the phase of the main signal SRm, which is the reverse phase signal of the main signal SRm, and is supplied to the sound signal generation signal generation circuit 36 (1). In the generation of the auxiliary signal SRa, there are cases where the phase is not only delayed but also the phase is delayed and the amplitude is attenuated.

  As described above, the main signal generation circuit 34R and the auxiliary signal generation circuit 35R are formed from the surround right channel audio signal SR in order to form an audio signal for localizing the sound image to the right rear of the listener. Then, processing is performed to generate signals that have opposite phases and that have adjusted transfer characteristics (frequency characteristics).

  Each of the sound case signal generating circuits 36 (1), 36 (2), 36 (3), and 36 (4) generates a sound case signal for outputting the supplied sound signal as a plane wave. . The sound signal is a signal that synthesizes the wavefront by being emitted as sound waves by the array speaker system SPAr, and is a multi-channel signal. In the playback apparatus of this embodiment, the array speaker system SPAr is formed by arranging 16 speakers as described above, and the sound case signal generating circuits 36 (1), 36 (2 ), 36 (3), and 36 (4) each form a sound signal for 16 channels.

  In the playback apparatus of this embodiment, the sound case signal generating circuit 36 (1) forms a sound case signal from the auxiliary signal SRa formed from the surround right channel sound signal, and generates the sound case signal. The generation circuit 36 (2) forms a sound case signal from the main signal SRm formed from the sound signal of the surround right channel. In this case, the sound case signal generation circuit 36 (1) and the sound case signal generation circuit 36 (2) generate sound case signals that radiate as plane waves from opposite directions to the listening area.

  Specifically, the sound signal generating circuit 36 (1) emits a plane wave from the left side of the array speaker system SPAr toward the listening area where the listener is present, as viewed from the listener facing the array speaker system SPAr. A sound signal is generated from the auxiliary signal SRa. In addition, the sound case signal generation circuit 36 (2) emits a sound as a plane wave from the right side of the array speaker system SPAr toward the listening area where the listener is seen, as viewed from the listener facing the array speaker system SPAr. A case signal is generated from the main signal SRm. In this way, the sound signal generated from the main signal (normal phase signal) SRm and the sound signal generated from the auxiliary signal (reverse phase signal) SRa are radiated from the left and right opposite directions. In this way, the array speaker system SPAr can be radiated.

  Similarly, the sound case signal generation circuit 36 (3) forms a sound case signal from the auxiliary signal SLa formed from the sound signal of the surround left channel, and the sound case signal generation circuit 36 (4) A sound signal is formed from the main signal SLm formed from the left channel audio signal. In this case, the sound case signal generating circuit 36 (3) and the sound case signal generation circuit 36 (4) generate sound case signals that radiate as plane waves from opposite directions to the listening area.

  That is, the sound signal generating signal generation circuit 36 (3) emits sound as a plane wave from the right side of the array speaker system SPAr toward the listening area where the listener is seen, as viewed from the listener facing the array speaker system SPAr. The case signal is generated from the auxiliary signal SLa. In addition, the sound case signal generation circuit 36 (4) emits sound as a plane wave from the left side of the array speaker system SPAr toward the listening area where the listener is seen, as viewed from the listener facing the array speaker system SPAr. A case signal is generated from the main signal SLm. By doing so, the sound signal generated from the main signal (normal phase signal) SLm and the sound signal generated from the auxiliary signal (reverse phase signal) SLa are radiated from the left and right opposite directions. In this way, the array speaker system SPAr can be radiated.

  The sound signal generation signals for 16 channels formed for each of the sound signal generation signal generation circuits 36 (1), 36 (2), 36 (3), and 36 (4) are supplied to the mixer 37. The mixer 37 generates 16 sound case signals (each of 16 channels) supplied from each of the sound case signal generation circuits 36 (1), 36 (2), 36 (3), and 36 (4). The four main sound signals SLm and SRm and the left and right auxiliary signals SLm and SRm are mixed (mixed) for each of the 16 channels to form the array speaker system SPAr. The sound signal generation signal for 16 channels supplied to each of the 16 speakers is formed and supplied to the n-channel amplifier circuit 38.

  In this embodiment, the n-channel amplifier circuit 38 includes an audio signal amplifier circuit for 16 channels corresponding to the 16 speakers constituting the array speaker system SPAr. Upon receiving the signal, each is amplified and supplied to each of the 16 speakers constituting the array speaker system SPAr.

  From each of the 16 speakers constituting the array speaker system SPAr, a sound case signal formed from the surround left channel main signal SLm and a sound case signal formed from the surround left channel auxiliary signal SLa. And the sound wave corresponding to the sound case signal formed by mixing the sound case signal formed from the surround right channel main signal SRm and the sound case signal generated from the surround right channel auxiliary signal SRa as a wavefront. Radiated to reach.

  As a result, in any of a relatively wide listening area, when the listener is facing the front where the array speaker system SPAr is installed, the sound of the surround left channel and the sound of the surround right channel are left. It is made possible to listen so as to come from the rear and the right rear.

  In other words, the sound emitted from each of the array speaker systems SPAr can also generate sound images on the left rear and right rear of the listener in a wide range of the listening area for the sound that should arrive from the left rear and right rear of the listener. This is a case where a relatively wide listening area (reproduction sound field) where the reproduced sound can be heard as having a sense of presence can be formed by localization, and the reproduced sound is listened to by a plurality of people. However, it is possible to prevent the sound that can be heard from being greatly different depending on the position of the listener, and to form a uniform reproduced sound field in a wide range of the listening area.

  The subwoofer channel audio signal, left channel audio signal, center channel audio signal, and right channel audio signal are subwoofer channel speaker SPW, left channel speaker SPL, and center channel speaker arranged in front of the listener. Sound is emitted from the SPC and right channel speaker SPR.

  Therefore, a speaker in which all 5.1 channel audio signals including the surround left channel audio signal and the surround right channel audio signal whose sound images are localized behind the listener are arranged in front of the listener. And a uniform reproduction sound field can be formed in a wide range of the listening area.

[Main signal generation circuit, auxiliary signal generation circuit, sound signal generation signal generation circuit]
Next, main signal generation circuits 34L and 34R, auxiliary signal generation circuits 35L and 35R, and sound case signal generation circuits 36 (1), 36 (2), 36 (3), 36 (4) will be described in detail.

[About the main signal generation circuits 34L and 34R and the auxiliary signal generation circuits 35L and 35R]
The main signal generation circuits 34L and 34R and the auxiliary signal generation circuits 35L and 35R will be described separately for the surround left channel and the surround right channel. First, the main signal generation circuit 34L and the auxiliary signal generation circuit 35L provided for the surround left channel will be described.

  FIG. 2 is a diagram illustrating a system in which the main signal SLm is generated from the audio signal SL of the surround left channel and the main signal SLm reaches the listening area as a plane wave. As shown in FIG. 2, in the main signal generation circuit 34L to which the surround left channel audio signal SL is supplied, as described above, transmission of the audio signal SL when a plane wave arrives from the left front to the left ear. The characteristic HLS is canceled, and the main signal SLm subjected to characteristic correction so that the transfer characteristic HLL from the left rear to the left ear can be reproduced in the left ear is generated.

  The main signal SLm for the surround left channel formed in this way is supplied to the sound signal generating signal generation circuit 36 (4), and is sent to the listeners A, B, C from the left side of the array speaker system SPAr. The sound signal is generated as a sound wave to be output as an incoming plane wave. This signal is mixed with other signals in the mixer 37 (not shown in FIG. 2), and corresponding to the array speaker system SPAr through the 16-channel amplifier circuit 38. The sound is supplied to the speaker and emitted. The inclination of the plane wave is in the range of 2 degrees to 10 degrees with respect to the sound emitting surface of the array speaker system SPAr.

  However, in the case of only the main signal SLm, the transfer characteristic HLR from the left rear to the right ear is not reproduced to the right ear, and a signal including an error reaches the listener. This is a clue to the perception of the sound image forward, and depending on the listener, the sound image perception behind may not occur. Therefore, an auxiliary signal is generated to reduce the influence of the clues for localization.

  FIG. 3 is a diagram illustrating a system in which the auxiliary signal SLa is generated from the audio signal SL of the surround left channel and the auxiliary signal SLa reaches the listening area as a plane wave. As shown in FIG. 3, the auxiliary signal generation circuit 35L to which the surround left channel audio signal SL is supplied includes a characteristic correction circuit 35L1 for generating the same signal as the main signal SLm, and a phase amplitude processing circuit 35L2. ing.

  The characteristic correction circuit 35L1 is configured in the same manner as the main signal generation circuit 34L described with reference to FIG. 2, and a plane wave is generated from the front left to the left ear with respect to the audio signal SL of the surround left channel supplied thereto. The transfer characteristic HLS when it arrives is canceled, and a signal that has been subjected to characteristic correction so that the transfer characteristic HLL from the left rear to the left ear can be reproduced in the left ear, that is, the same signal as the main signal SLm is generated.

  The signal generated in the characteristic correction circuit 35L1 is supplied to the phase amplitude processing circuit 35L2. The phase / amplitude processing circuit 35L2 inverts the phase of the same signal as the main signal SLm to form a reverse phase signal of the same signal as the main signal SLm, and at least the phase of the reverse phase signal of the same signal as the main signal SLm. , The auxiliary signal SLa that interferes with the main signal SLm in the listening area is generated.

  When the listening area to be controlled is wide, the auxiliary signal SLa is generated by delaying the phase and attenuating the amplitude of the reverse phase signal of the main signal SLm. Thus, the reason why the auxiliary signal SLa is generated by delaying the phase of the reverse phase signal of the main signal SLm is to make the main signal SLm reach the listener earlier at any position in the listening area. The reason why the auxiliary signal SLa is generated by attenuating the amplitude of the same signal as the main signal SLm is to prevent the auxiliary signal SLa from becoming larger than the main signal SLm.

  The auxiliary signal SLa for the surround left channel formed in this way is supplied to the sound signal generating signal generation circuit 36 (3), and to the listeners A, B, C from the right direction of the array speaker system SPAr. The sound signal is generated as an incoming plane wave for sound output, and is mixed with other signals in a mixer 37 (not shown in FIG. 3). The sound is supplied to the speaker and emitted. The inclination of the plane wave is opposite to the direction of the sound signal generated by the sound signal generation signal generating circuit 36 (4) that forms the sound signal generation signal for the main signal SLm, and the array speaker system SPAr. With respect to the sound emission surface, the range is about 2 to 10 degrees.

  In the listening area, the transfer characteristic to the left ear due to interference between the main signal SLm and the auxiliary signal SLa causes a peak dip when viewed in a narrow frequency range, but in the spectral envelope of the entire frequency band, It becomes a transfer characteristic. The fact that the spectral envelope of the entire frequency band is a transfer characteristic from the rear is a clue to the perception of the rear sound image.

  Even if both the main signal SLm and the auxiliary signal SLa are presented from the front, the interaural difference characteristic when viewed in a narrow frequency range due to the interference between the main signal SLm and the auxiliary signal SLa is a sound wave coming from the front. This is different from the interaural difference characteristic generated in both ears.

  Conventionally, it is known that when the cross-correlation coefficient between both ears decreases, the sound image is localized near or behind the listener, but in a narrow frequency range due to interference between the main signal SLm and the auxiliary signal SLa. The binaural correlation coefficient is lowered, which acts as a clue to emphasize the backward sound image perception clue. Further, the effect of enhancing the backward sound image perception cues can reduce the influence of individual differences in transfer characteristics that are cues for backward localization.

  Here, processing in the main signal generation circuit 34L and the auxiliary signal generation circuit 35L that processes the audio signal SL of the surround left channel described with reference to FIGS. 2 and 3 will be described in detail with reference to waveform diagrams. .

  If sounds corresponding to sound signals having opposite phases are emitted simultaneously from the left and right, the sound image of the emitted sound is brought close to the vicinity of the listener. However, in this case, the sound image is blurred and not very clear. Therefore, in the reproducing apparatus of this embodiment, as described above, in the main signal generation circuit 34L and the auxiliary signal generation circuit 35L, the main signal SLm and the auxiliary signal SLa that have opposite phases to each other and whose transfer characteristics are corrected are provided. Although these will be described in detail later, sound is emitted as plane waves arriving from opposite directions from each other by using a wavefront synthesis technique.

  In this case, since the arrival time of the sound differs depending on the place where the emitted sound is heard, it is necessary to adjust this. FIG. 4 is a diagram for explaining a waveform obtained when a response in the vicinity of the listener's left and right ears is observed using a 1 kHz burst signal.

  For example, as shown in FIG. 2, from an array speaker system SPAr consisting of 16 speakers, a sound signal SL of surround left channel is simply output as a 1 kHz burst signal as a positive phase plane wave (positive phase signal), When the response of the listener A in the left ear (upper part of FIG. 4A) and the response of the right ear (lower part of FIG. 4A) are observed at the position of the listener A, the waveform of the lower part of FIG. It can be seen that the phase of is slightly delayed. That is, when the sound signal of the surround left channel is output as a positive phase plane wave from the array speaker system SPAr, the arrival time of the sound output sound to the left ear is earlier than the arrival time to the right ear.

  However, as shown in FIG. 3, from an array speaker system SPAr composed of 16 speakers, a 1 kHz burst signal is inverted in phase as an audio signal SL of the surround left channel, and a sound is generated as a reverse plane wave (reverse phase signal). When the output and the response in the left ear of the listener A at the position of the listener A (the upper stage in FIG. 4B) and the response in the right ear (the lower stage in FIG. 4B) are observed, the waveform in the lower stage in FIG. It can be seen that the phase of the upper waveform is slightly delayed. That is, when the sound signal of the surround left channel is output from the array speaker system SPAr as an antiphase plane wave, the arrival time of the sound output sound to the right ear is earlier than the arrival time to the left ear.

  However, depending on the listening environment as shown in FIG. 2 and FIG. 3, the plane wave of the positive phase signal is the reverse phase signal for all of the listeners A, B, and C (even the listener at the right end). If the sound reaches the left ear faster than the plane wave, and all of the listeners A, B, and C (even the listener at the right end) do not increase the level of the reverse phase signal, the sound of the surround left channel Cannot be localized to the left rear of the listener.

  For this reason, as described above, in the auxiliary signal generation circuit 35L, it is necessary to perform a process of delaying at least the phase or further attenuating the amplitude of the reverse phase signal obtained by inverting the phase of the audio signal of the surround left channel. Arise. In this case, the delay is 0.25 msec (milliseconds) when the frequency is lower than 2 kHz (kilohertz), which has a great influence on the perception of the sound image direction, and the range where the listener is present is about 1.2 m (meters) wide. The amplitude attenuation is about 0.95 times (−0.45 dB (decibel)).

  Then, if a 1 kHz burst signal is used as the audio signal SL of the surround left channel, and this is processed and output by the audio data processing system 3 shown in FIG. 1, as shown in FIG. 4C, The positive phase signal (upper stage in FIG. 4C) and the reverse phase signal (lower stage in FIG. 4C) are surround in which there is no phase delay or advance, and the left and right sound images of the listener are localized by adjusting the transfer characteristics. The sound signal of the left channel can be emitted.

  In this way, the main signal generation circuit 34L forms a positive-phase main signal SLm in which transfer characteristics are adjusted for the surround left channel audio signal SL, and the auxiliary signal generation circuit 35L forms the surround left channel audio signal SL. The phase of the same signal as the positive-phase main signal SLm with the transfer characteristics adjusted is reversed, and the phase-delay processing, or the phase-delay processing and the amplitude attenuation processing are performed, and the auxiliary signal SLa having the opposite phase to the main signal SLm. Form.

  Then, a sound case signal for the surround left channel is generated in a sound case signal generating circuit 36 (3), 36 (4), which will be described later, and supplied to the array speaker system SPAr through the mixer 37 and the n channel amplifier circuit 38. The sound image is output and the sound image is localized at the left rear of the listener at any position in the wide range of the listening area.

  Next, the main signal generation circuit 34R and the auxiliary signal generation circuit 35R provided for the surround right channel will be described. The main signal generation circuit 34R and the auxiliary signal generation circuit 35R are basically the same as the main signal generation circuit 34L and the auxiliary signal generation circuit 35L for the surround left channel described above, except that the audio signals to be processed are different. It has a function and operates similarly.

  FIG. 5 is a diagram illustrating a system in which the main signal SRm is generated from the surround right channel audio signal SR and the main signal SRm reaches the listening area as a plane wave. As shown in FIG. 5, in the main signal generation circuit 34R to which the surround right channel audio signal SR is supplied, the transfer characteristic HRS when the plane wave arrives from the right front to the right ear is canceled for the audio signal SR. Then, the main signal SRm subjected to the characteristic correction so that the transfer characteristic HRR from the right rear to the right ear can be reproduced in the right ear is generated.

  The main signal SRm for the surround right channel formed in this way is supplied to the sound signal generating signal generation circuit 36 (2), and from the right side of the array speaker system SPAr to the listeners A, B, and C. The sound signal is generated as a sound wave to be output as an incoming plane wave, and is mixed with other signals in a mixer 37 (not shown in FIG. 5). The sound is supplied to the speaker and emitted.

  However, in the case of only the main signal SRm, the transfer characteristic HRL from the right rear to the left ear is not reproduced to the left ear, and a signal including an error reaches the listener. This is a clue to the perception of the sound image forward, and depending on the listener, the sound image perception behind may not occur. Therefore, the auxiliary signal SRa for reducing the influence of the clues for the front localization is generated.

  FIG. 6 is a diagram illustrating a system in which the auxiliary signal SRa is generated from the sound signal SR of the surround right channel and the auxiliary signal SRa reaches the listening area as a plane wave. As shown in FIG. 6, the auxiliary signal generation circuit 35R to which the surround right channel audio signal SR is supplied includes a characteristic correction circuit 35R1 for generating the same signal as the main signal SRm, and a phase amplitude processing circuit 35R2. ing.

  The characteristic correction circuit 35R1 is configured in the same manner as the main signal generation circuit 34R described with reference to FIG. 5. With respect to the audio signal SR of the surround right channel supplied thereto, a plane wave is generated from the right front to the right ear. The transfer characteristic HRS when it arrives is canceled, and a signal that has been subjected to characteristic correction so that the transfer characteristic HRR from the right rear to the right ear can be reproduced in the right ear, that is, the same signal as the main signal SRm is generated.

  The signal generated in the characteristic correction circuit 35R1 is supplied to the phase amplitude processing circuit 35R2. The phase amplitude processing circuit 35R2 inverts the phase of the same signal as the main signal SRm to form a reverse phase signal of the main signal SRm, and delays at least the phase of the reverse phase signal of the main signal SRm. An auxiliary signal SRa that interferes with the main signal SRm is generated in the listening area.

  When the listening area to be controlled is wide, the auxiliary signal SRa is generated by delaying the phase and attenuating the amplitude of the same signal as the main signal SRm. Thus, the reason why the auxiliary signal SRa is generated by delaying the phase of the same signal as the main signal SRm is to make the main signal SRm reach the listener earlier at any position in the listening area. The reason why the auxiliary signal SRa is generated by attenuating the amplitude of the same signal as the main signal SRm is to prevent the auxiliary signal SRa from becoming larger than the main signal SRm.

  The auxiliary signal SRa for the surround right channel formed in this way is supplied to the sound signal generating signal generation circuit 36 (1), and from the left side of the array speaker system SPAr to the listeners A, B, and C. The sound signal is generated as a sound wave to be output as an incoming plane wave, and is mixed with other signals in a mixer 37 (not shown in FIG. 5). The sound is supplied to the speaker and emitted.

  Note that also in the auxiliary signal generation circuit 35R that forms the auxiliary signal SRa from the audio signal SR of the surround right channel, the phase delay of the main signal SRm with respect to the reverse phase signal is about 0.25 msec (milliseconds), and the amplitude is The attenuation is about 0.95 times (−0.45 dB (decibel)).

  Further, the slope of the sound case signal as a plane wave in the sound case signal generation circuit 36 (1), 36 (2) is the case of the sound as a plane wave in the sound case signal generation circuit 36 (1), 36 (2). Similar to the inclination of the generated signal, it is about 2 to 10 degrees with respect to the sound emitting surface of the array speaker system SPAr. Of course, the direction of the inclination of the sound case signal as a plane wave formed by the sound case signal generation circuit 36 (1) and the sound case signal generation circuit 36 (2) is reversed.

  In the listening area, the transfer characteristic to the right ear has a peak dip in the narrow frequency range due to the interference between the main signal SRm and the auxiliary signal SRa. However, in the spectral envelope of the entire frequency band, It becomes a transfer characteristic. The fact that the spectral envelope of the entire frequency band is a transfer characteristic from the rear is a clue to the perception of the rear sound image.

  Even if both the main signal SRm and the auxiliary signal SRa are presented from the front, the interaural difference characteristic when viewed in a narrow frequency range due to the interference between the main signal SRm and the auxiliary signal SRa is a sound wave coming from the front. This is different from the interaural difference characteristic generated in both ears.

  As described above, conventionally, it is known that when the cross-correlation coefficient between both ears decreases, the sound image is localized near or behind the listener, but interference between the main signal SRm and the auxiliary signal SRa. As a result, the interaural correlation coefficient in a narrow frequency range is lowered, which acts as a clue to emphasize the backward sound image perception clue. Further, the effect of enhancing the backward sound image perception cues can reduce the influence of individual differences in transfer characteristics that are cues for backward localization.

  Note that, as described with reference to FIG. 4, the signal formed by processing through the main signal generation circuit 34L and the auxiliary signal generation circuit 35L for the surround left channel is also a positive phase signal for the audio signal of the surround right channel. And the reverse transmission signal may cause a phase shift or a level imbalance. Therefore, the auxiliary signal generation circuit 35R also performs phase delay processing, phase delay processing, and amplitude attenuation processing. Will do.

  In this way, the main signal generation circuit 34R forms a positive-phase main signal SRm with the transfer characteristic adjusted for the surround right channel audio signal SR, and the auxiliary signal generation circuit 35R forms the surround right channel audio signal SR. The phase of the same signal as the positive-phase main signal SRm with the transfer characteristic adjusted is inverted, and the phase-delay processing or the phase-delay processing and the amplitude attenuation processing are performed to provide the auxiliary signal SRa having the opposite phase to the main signal SRm. Form.

  Then, a sound case signal for the surround right channel is generated in a sound case signal generation circuit 36 (1) and 36 (2), which will be described later, and supplied to the array speaker system SPAr through the mixer 37 and the n channel amplifier circuit 38. The sound image is output and the sound image is localized at the left rear of the listener at any position in the wide range of the listening area.

  2 to 6 mainly focus on the listener A. However, since the sound emitted from the array speaker system SPAr is transmitted by a plane wave, the listener B And the listener C can cause the same phenomenon.

  In this way, each of the surround left channel audio signal SL and the surround right channel audio signal SR is processed, and is emitted as a plane wave from the array speaker system SPAr arranged in front of the listener, thereby producing a surround sound. As shown in FIGS. 2 and 3, the sound image of the left channel audio signal is localized at the position of the virtual speaker VSL on the left rear side of the listener, and the sound image of the surround right channel audio signal is shown in FIG. As shown in FIG. 6, a good reproduction sound field can be formed by localization to the position of the virtual speaker VRL at the right rear of the listener.

  In addition, the sound emitted from the array speaker system SPAr is a sound signal that is output as a plane wave in the speech synthesis signal generation circuits 36 (1), 36 (2), 36 (3), and 36 (4). Therefore, at any position within a relatively large listening area, the surround left channel audio signal is placed at the left rear of the listener, and the surround right channel audio signal is set by the listener. A sound image can be localized appropriately on the right rear side, and a good reproduction sound field can be formed.

[Sound signal generation circuit]
Next, a sound field generation and control technique (wavefront synthesis technique) used in each of the sound case signal generating circuits 36 (1), 36 (2), 36 (3), and 36 (4) will be described. 7 to 11 are diagrams for explaining a sound field generation and control technique (wavefront synthesis technique). As a method for controlling the sound field in a three-dimensional space, for example, it is shown in “Research on three-dimensional virtual reality based on Kirchoff integral equation”, “Waseda University, Research Center for Science and Engineering, Acoustic Information Processing Laboratory, Yoshio Yamazaki,” As shown, there is a method using the Kirchhoff integration formula as follows.

  That is, assuming a closed curved surface S that does not include a sound source as shown in FIG. 7, the sound field in the closed curved surface S can be expressed by Kirchhoff's integral formula. In FIG. 7, p (ri) is the sound pressure at the point ri in the closed surface S, p (rj) is the sound pressure at the point rj on the closed surface S, n is the normal at the point rj, and un (rj) is the modulus. The particle velocity in the direction of line n, | ri−rj |, is the distance between point ri and point rj.

  Kirchhoff's integral formula is expressed by equation (1) in FIG. 8, and if the sound pressure p (rj) on the closed surface S and the particle velocity un (rj) in the direction of the normal n can be completely controlled, the closed surface S It means that the sound field inside can be completely reproduced.

  In the equation (1), ω is an angular frequency represented by ω = 2πf where f is an audio frequency, ρ is an air density, and Gij is represented by the equation (2) in FIG. It is what is done.

  Equation (1) is for a steady sound field, but the same can be said for a transient sound field by controlling the instantaneous values of sound pressure p (rj) and particle velocity un (rj).

  Thus, in the sound field design by Kirchhoff's integral formula, it is only necessary to reproduce the sound pressure p (rj) and the particle velocity un (rj) on the virtual closed curved surface S. Since it is impossible to control the sound pressure p (rj) and the particle velocity un (rj) at the continuous points, the sound pressure p (rj) and the particle velocity un ( On the premise that rj) is constant, the closed curved surface S is discretized.

  When the closed surface S is discretized at N points, equation (1) in FIG. 8 is expressed by equation (3) in FIG. 8, and the sound pressure p (rj) at N points on the closed surface S and By reproducing the particle velocity un (rj), the sound field in the closed curved surface S can be completely reproduced.

  As a system for reproducing the sound pressure p (rj) and the particle velocity un (rj) at the N points with M sound sources, a system as shown in FIG. 9 is considered.

  In this system, the audio signal from the signal source 201 is supplied to the speaker 203 through the filter 202, and the sound pressure is measured at N points on the boundary surface of the control region 204. The particle velocity un (rj) in the normal direction is approximately obtained from the sound pressure signal by the two-microphone method.

  At this time, in order to reproduce the sound pressure p (rj) and the particle velocity un (rj) at the N point, the sound pressure at the 2N point should be equal to the original sound field. This results in the problem of obtaining a value such that the sound pressure at the 2N point is closest to the original sound field as the transfer function Hi (i = 1 to M) of the filter 2.

  Therefore, Cij is a transfer function between the sound source i (i = 1 to M) and the sound receiving point j (j = 1 to 2N) in the reproduction sound field, and Hi is a transfer function of the filter in the previous stage of the sound source i. An evaluation function for minimizing the difference between the reproduction sound field and the original sound field as represented by the equation (4) in FIG. 8, where Pj is a transfer function between the sound source and the sound receiving point j in the original sound field. Think of J.

  In order to obtain the transfer function Hi that minimizes the evaluation function J expressed by the equation (4), the equation (5) in FIG. 8 may be solved.

  Furthermore, as an extension of Kirchhoff's integral formula to a half space, as shown in FIG. 10, a sound source 205 is arranged in a space on one side (left side in the figure) of the boundary surface S1, and in a space on the opposite side (right side in the figure). Assuming a listening area 206 that does not include a sound source, if the sound pressure and particle velocity at all points on the boundary surface S1 or discrete points as described above are controlled by Kirchhoff's integral formula, A desired sound field can be realized in the listening area 206 not included.

  Specifically, as shown in FIG. 11, a plurality of speakers SP1, SP2,... SPm are arranged on the left side (one side) of a finite length control line (boundary line) S2, and a plurality of controls are arranged on the control line S2. By setting the points C1, C2... Ck and controlling the sound pressure (amplitude) and phase at each control point C1, C2... Ck, the right side of the control line S2 (speakers SP1, SP2... SPm side) In the listening area on the opposite side, the listener 7 can hear the sound from the speakers SP1, SP2,... SPm as the sound from the virtual point sound source 208 on the left side of the control line S2 (speakers SP1, SP2,... SPm side). Like that.

  In this way, by controlling the phase (delay time) and sound pressure (sound pressure level) of the audio signal supplied to each speaker, it is possible to generate and control the target sound field. By using such a sound field generation and control technique (wavefront synthesis technique), each of the sound case signal generation circuits 36 (1), 36 (2), 36 (3), and 36 (4) As described above, for the corresponding signals among the main signals SLm, SRm and auxiliary signals SLa, SRa generated by correcting the characteristics of the surround left channel audio signal SL and the surround right channel audio signal SR, A process for controlling the phase and the sound pressure is performed to generate a sound case signal that is acoustically output as a plane wave and that is localized at the rear of the listener.

  As described above, in the reproducing apparatus of this embodiment, the spectrum of the transfer characteristic that is localized backward by the interference between the main signal SLm and the auxiliary signal SLa and the interference between the main signal SRm and the auxiliary signal SRa. The envelope is transmitted to the ears of the listener, and the main signal SLm and the auxiliary signal SLa in the listening area and the sound waves coming from the front due to the interference of the main signal SRm and the auxiliary signal SRa are generated between both ears. It becomes a difference between both ears, which is different from the difference, and the transmission characteristic for rearward localization is emphasized psychoacoustically, and the sound image can be perceived backward.

  In addition, the sound of the sound image to be localized behind the listener is output as a plane wave from the array speaker system SPAr arranged in front of the listener by using a wavefront synthesis technique, so a wider listening area. The sound image of the sound of the surround left channel and the sound of the surround right channel can be satisfactorily listened to as being localized behind the listener.

[Configuration example of audio data processing system 3]
[About the audio data processing system 3 of the playback apparatus shown in FIG. 1]
Next, the configuration of the audio data processing system 3 of the playback apparatus of this embodiment will be summarized. FIG. 12 is a diagram showing the configuration of the audio data processing system 3 of the playback apparatus of this embodiment in which processing units are grouped for each audio channel. As shown in FIG. 1, the audio data processing system 3 of the playback apparatus of this embodiment includes an audio data decoder 31, a time axis adjustment circuit 32, amplification circuits 33W and 33F, a subwoofer channel speaker SPW, a front Speakers SPL, SPC, SPR, main signal generation circuits 34L, 34R, auxiliary signal generation circuits 35L, 35R, sound field signal generation circuits 36 (1), 36 (2), 36 (3), 36 (4), mixer 37 , An n-channel amplifier circuit 38 and an array speaker system SPAr.

  Then, the playback apparatus of this embodiment emits sound from the array speaker system SPAr arranged in front of the listener for the sound signal that localizes the sound image behind the listener, and other sound signals, that is, The subwoofer channel audio signal W, the left channel audio signal R, the center channel audio signal C, and the right channel audio signal R are provided separately from the array speaker system SPAr, and are arranged in front of the listener. Sound is emitted from the woofer channel speaker SPW, the left channel speaker SPL, the center channel speaker SPC, and the right channel speaker SPR.

  Then, the audio data processing system 3 of the playback apparatus of this embodiment shown in FIG. 1 is summarized as shown in FIG. 12, an audio data decoder 31 and a subwoofer channel processing unit (in FIG. 12, woofer channel processing). 51), left / right channel processing unit 52, center channel processing unit 53, rear localization signal processing unit 54, rear localization enhancement signal processing unit 55, sound case application 16ch signal generation unit 56, It is equipped with.

  The subwoofer channel processing unit 51 is a part including a time axis adjustment circuit 32 and an amplifier circuit 33W, and the audio signal processed here is supplied to the subwoofer channel speaker SPW. The left / right channel processing unit 52 and the center channel processing unit 53 are portions including a time axis correction circuit 32 and an amplification circuit 33F in FIG.

  Therefore, the left / right channel processing unit 52 is a portion including the time axis adjustment circuit 32 and the amplification circuit 33F. Among the audio signals processed here, the left channel audio signal L is sent to the left channel speaker SPL. Also, the right channel audio signal R is supplied to the right channel speaker SPR.

  The center channel processing unit 53 is a part composed of the time axis adjustment circuit 32 and the amplification circuit 33F, and the audio signal C processed here is supplied to the center channel speaker SPC. As described above, in the playback apparatus of this embodiment, for the front channel audio signal including the subwoofer channel audio signal, the subwoofer channel speaker SPW provided separately from the array speaker system SPAr, the left channel Sound is emitted from each of the speaker SPL, the center channel speaker SPC, and the right channel speaker SPR.

  The rear localization signal processing unit 54 is a portion including main signal generation circuits 34L and 34R, and receives the supply of the surround left channel audio signal SL and the surround right channel audio signal SR supplied thereto, For the sound signal of the surround left channel, the main signal SLm that cancels the transfer characteristic when a plane wave arrives from the left front to the left ear and reproduces the transfer characteristic from the left rear to the left ear to the left ear is used. For the sound signal of the surround right channel generated, the transfer characteristic when the plane wave arrives from the right front to the right ear is canceled, and the transfer characteristic from the right rear to the right ear can be reproduced to the right ear. The signals SRm are generated, and each of them is supplied to the sound case generating 16ch signal generating unit 56.

  The rear localization emphasis signal processing unit 55 is a part composed of auxiliary signal generation circuits 35L and 35R, and receives supply of the surround left channel audio signal SL and the surround right channel audio signal SR supplied thereto. Then, the phase of the same signal as the main signal SLm is inverted to generate an anti-phase signal, and the phase of the anti-phase signal is delayed, or the phase is delayed and the amplitude is attenuated to generate the auxiliary signal SLa. Further, the same signal as the main signal SRm is inverted in phase to form an anti-phase signal, the phase of the anti-phase signal is delayed, or the phase is delayed and the amplitude is attenuated to generate the auxiliary signal SRa. Is supplied to the 16-channel signal generation unit 56 for sound cases.

  The voice synthesis 16ch signal generation unit 56 includes a sound case signal generation circuit 36 (1), 36 (2), 36 (3), 36 (4), a mixer 37, and an n-channel amplification circuit 38. 16 channels of audio signals corresponding to each of the 16 speakers constituting the array speaker system SPAr from the main signals SLm, SRm, and auxiliary signals SLa, SRa, and having the phase and the sound pressure. By adjusting, the sound is output as a plane wave, and a sound signal is generated behind the listener to localize the sound image, and this signal is supplied to the corresponding speaker of the array speaker system SPAr.

  As a result, the sound signal to be localized in the rear of the listener is emitted as a plane wave from the array speaker system SPAr, so that it can be transmitted to the left rear and right rear of the listener at any location in the listening area. For audio signals that should be localized, the sound image is well localized to the left rear and right rear of the listener, and even when multiple listeners listen to the same playback sound at the same time, An optimal sound field environment with a feeling can be provided. Of course, the subwoofer channel audio signal and the front channel audio signal are emitted from the corresponding speakers SPW, SPL, SPC, and SPR, and these front channel audio signals are also provided with appropriate acoustic output.

[Another configuration example of the audio data processing system 3]
As described above, the audio data processing system 3 of the playback apparatus described with reference to FIGS. 1 and 12 is an array speaker system in which only the audio signal that localizes the sound image behind the listener is arranged in front of the listener. Sound was emitted from SPAr. However, it is not limited to this. That is, in addition to the audio signal that localizes the sound image behind the listener, the subwoofer audio signal W, the left channel audio signal R, the center channel audio signal C, and the right channel audio signal R are also used for the array speaker. The audio data processing system 3 can also be configured to emit sound from the system SPAr.

  FIG. 13 shows a sound configured to emit sound from the array speaker system SPAr for a so-called front channel audio signal including a subwoofer channel audio signal in addition to an audio signal for localization of the sound image behind the listener. FIG. 10 is a block diagram for explaining another configuration example of the data processing system 3.

  Other configuration examples of the audio data processing system 3 shown in FIG. 13 are basically the same except that the subwoofer channel speaker SPW, the left channel speaker SPL, the center channel speaker SPC, and the right channel speaker SPR are not provided. 12 is configured in the same manner as the audio data processing system 3 shown in FIG.

  However, since the audio signal of the front channel including the subwoofer channel is also emitted from the array speaker system SPAr, the subwoofer channel processing unit (described as the woofer channel processing unit in FIG. 13) 51A, The configurations of the right channel processing unit 52A, the center channel processing unit 53A, and the sound case generating 16ch signal generation unit 56A are different from the audio data processing system 3 shown in FIG.

  The audio data decoder 31, the rear localization signal processing unit 54, the rear localization enhancement signal processing unit 55, and the array speaker system SPAr are configured in the same manner as the audio data processing system 3 shown in FIG. Therefore, the same reference numerals as those in the case of the audio data processing system 3 shown in FIG.

  In another configuration example of the audio data processing system 3 shown in FIG. 13, the audio signals output from the subwoofer channel processing unit 51A, the left / right channel processing unit 52A, and the center channel processing unit 53A are also used. It is configured to be supplied to the array speaker system SPAr via the sound case generating 16ch signal generation unit 56A.

  Therefore, the subwoofer channel processing unit 51A, the left / right channel processing unit 52A, the center channel processing unit 53A, and the sound case generating 16ch signal generation unit 56A are included in the audio data processing system 3 shown in FIG. The configuration is slightly different from the corresponding parts. More specifically, each of the subwoofer channel processing unit 51A, the left / right channel processing unit 52A, and the center channel processing unit 53A is a part corresponding to the time axis adjustment circuit 32.

  The sound case generating 16ch signal generating unit 56A also includes a sound case generating signal generating circuit corresponding to the subwoofer channel processing unit 51A, the left / right channel processing unit 52A, and the center channel processing unit 53A. A mixer that also mixes the sound signal from the subwoofer channel processing unit 51A, left / right channel processing unit 52A, and center channel processing unit 53A, and amplifies the audio signals of each of the 16 channels from the mixer. This also includes an amplification circuit for 16 channels.

  That is, the sound signal from the subwoofer channel processing unit 51A, the left / right channel processing unit 52A, and the center channel processing unit 53A is also supplied to the array speaker system SPAr for output from the array speaker system SPAr. Must be generated. For this reason, the sound case signal generating circuit that forms the sound case signal based on the sound signals from the subwoofer channel processing unit 51A, the left / right channel processing unit 52A, and the center channel processing unit 53A The composition 16ch signal generation unit 56A is provided.

  In this case, the sound signal generating circuit corresponding to each of the subwoofer channel processing unit 51A, the left / right channel processing unit 52A, and the center channel processing unit 53A uses the wavefront synthesis technique as described above, By controlling the sound pressure and the sound pressure of the subwoofer channel, the left channel, the right channel, and the center channel, the sound wave from the virtual speaker is assumed to be at a predetermined position from the array speaker system SPAr while maintaining the respective characteristics. It is processed so that sound can be emitted.

  In other words, the subwoofer channel audio signal is the subwoofer channel audio signal, the left channel audio signal is the sound emitted from the left virtual speaker assumed at a predetermined position, and the center channel. Of the right channel as a sound emitted from the center virtual speaker assumed at a predetermined position, and the right channel sound signal as a sound emitted from the right virtual speaker assumed at a predetermined position, A sound signal is generated so that sound can be emitted from the array speaker system SPAr.

  More specifically, the center channel audio signal is assumed to be located at the center of the array speaker system SPAr, and the center channel audio signal is emitted radially from the center virtual speaker. To do. Assuming that the left virtual speaker is positioned at or near the left end of the array speaker system SPAr, the left channel audio signal is such that sound is emitted from the left virtual speaker. To emit sound. Similarly, the right channel audio signal is assumed to be located at or near the right end of the array speaker system SPAr, and the right channel so that sound is emitted from the right virtual speaker. The sound signal is emitted.

  The position of the center virtual speaker, the position of the left virtual speaker, and the position of the right virtual speaker can be assumed at various positions. The position of each virtual speaker can be assumed at various positions, for example, assuming that it is positioned behind the array speaker system SPAr. In addition, the subwoofer channel audio signal may be emitted by any method such as emitting sound from a virtual point sound source in front or emitting sound as a plane wave.

  In the case of another configuration example of the audio data processing system 3 shown in FIG. 13, the main signals SLm and SRm generated by the rear localization signal processing unit 54 and the rear localization enhancement signal processing unit 55 are generated. In addition to the auxiliary signals SLa and SRa, the sound signals of the subwoofer channel, the left channel, the right channel, and the center channel are also generated as sound signals. In this example, the signals are supplied to the 16-channel array speaker system SPAr. Thus, the sound signal of the front channel including the subwoofer channel is also emitted as a sound wave from the virtual speaker.

  Accordingly, in the case of another configuration example of the audio data processing system 3 shown in FIG. 13, 16 subwoofer channel speakers SPW, left channel speaker SPL, center channel speaker SPC, and right channel speaker SPR are not provided. By using the array speaker system SPAr consisting of the above speakers, the sound of each channel is acoustically output as a sound wave from the virtual speaker, and a good reproduction sound field where sound can be heard from a predetermined position in a wide range of the listening area is realized. be able to.

  Further, another configuration example of the audio data processing system 3 shown in FIG. 13 can be shown as shown in FIG. 14 in detail according to the playback device shown in FIG. That is, FIG. 14 shows another configuration example of the audio data processing system 3 shown in FIG. 13 in more detail. As shown in FIG. 14, the audio data decoder 31, the time axis adjustment circuit 32, the main signal generation circuits 34L and 34R, the auxiliary signal generation circuits 35L and 35R, the sound case signal generation circuits 36 (1) and 36 (2), Each of 36 (3), 36 (4), mixer 37, n-channel amplifier circuit 38, and array speaker system SPAr is provided in the same manner as in the case of the audio data processing system 3 shown in FIG.

  In the case of another configuration example of the audio data processing system 3 shown in FIG. 14, the sound signal generation signal generating circuit 39 (1) for the subwoofer channel is provided between the time axis adjusting circuit 32 and the mixer 37. A sound case signal generating circuit 39 (2) for the left channel, a sound case signal generating circuit 39 (3) for the center channel, and a sound case signal generating circuit 39 (4) for the right channel. It becomes the composition.

  Therefore, as shown by being surrounded by a dotted line in FIG. 14, portions corresponding to each front channel of the time axis adjustment circuit 32 are connected to the subwoofer channel processing unit 51A, the left / right channel processing unit 52A, and the center channel processing unit 53A. The main signal generation circuits 34L and 34R correspond to the rear localization signal processing unit 54, the auxiliary signal generation circuits 35L and 35R correspond to the rear localization enhancement signal processing unit 55, and the sound case signal generation circuit 36 ( 1), 36 (2), 36 (3), 36 (4), sound case signal generation circuit 39 (1), 39 (2), 39 (3), 39 (4), mixer 37, n-channel amplification The portion formed of the circuit 38 corresponds to a sound case application 16-channel signal generation unit.

  Each of the sound case signal generating circuits 39 (1), 39 (2), 39 (3), 39 (4) uses a wavefront synthesis technique, and the phase and sound pressure of the sound signals supplied to them are set. This is an audio signal to be adjusted and supplied to each of the speakers constituting the array speaker system SPAr, and for emitting the sound of the front channel including the subwoofer channel from the array speaker system SPAr as a sound wave from the virtual speaker. A sound signal is formed.

  The sound case signal for 16 channels formed for each of the sound case signal generation circuits 39 (1), 39 (2), 39 (3), and 39 (4) is supplied to the mixer 37, where , Main signals SLm, SRm and auxiliary signals SLa, SRa are mixed for each channel corresponding to 16 speakers constituting the array speaker system SPAr, and each speaker constituting the array speaker system SPAr through the n-channel amplifier circuit 38 In addition to the audio signal whose sound image is to be localized behind the listener, the front channel audio signal including the subwoofer channel is also appropriately processed and supplied to the array speaker system SPAr as a sound signal. Therefore, a good listening area can be formed by outputting the sound.

  As a result, only the array speaker system SPAr is used without using front channel speakers such as subwoofer channel speaker SPW, left channel speaker SPL, center channel speaker SPC, and right channel speaker SPR, which should be placed in front of the listener. By using this, it is possible to form a good reproduction sound field.

  Moreover, the surround left channel audio signal SL and the surround right channel audio signal SR are respectively located in the listening area by the functions of the rear localization signal processing unit 54 and the rear localization enhancement signal processing unit 55. Since the listener can listen to the sound whose sound image is localized in the left rear and right rear of the listener, even if multiple people listen to the playback sound at the same time, the optimal playback for each listener here A sound field can be provided.

  In the case of the example shown in FIGS. 13 and 14, that is, at least the sound signal L from the virtual speaker from the array speaker system arranged in front of the listener, for the left channel audio signal L and the right channel audio signal R. In the case of outputting as, it is possible to form a good reproduction sound field in a wide range by using the technique described in Japanese Patent Application No. 2005-119155.

  In the above-described embodiment, the array speaker system SPAr is described as being configured by arranging 16 speakers in which the distance between the centers of adjacent speakers is, for example, 10 cm (centimeter). This is not a limitation. For example, when the distance between the centers of adjacent speakers is, for example, 10 cm, it is possible to satisfactorily reproduce sound in a band up to 1.7 kHz (kilohertz). The number of speakers constituting the array speaker system and the distance between the centers of adjacent speakers can be appropriately changed according to the performance and size of the speakers to be used, the size of the listening area to be formed, and the like.

  The inclination angle of the sound signal formed from the main signals SLm and SRm and the sound signal generated from the auxiliary signals SLa and SRa with respect to the sound emitting surface of the array speaker system SPAr is preferably 2 to 10 degrees. However, there is no need to tilt it at all, or the main signal and auxiliary signal can be set differently, or the surround left channel audio signal can be differentiated from the surround right channel audio signal. Of course, an appropriate adjustment may be made.

  Further, although the playback apparatus according to the above-described embodiment has been described by way of example as applied to a playback apparatus of a home theater system that also includes a video signal playback system, the present invention is not limited to this. Needless to say, the present invention can also be applied to an audio apparatus that reproduces only audio data.

  That is, as in the playback apparatus of the above-described embodiment, the main signal and the auxiliary signal are generated for the audio signals of the left and right surround channels, and each is radiated as a plane wave from the opposite direction to the listening area. The present invention can be applied to various audio devices and audiovisual devices that perform sound reproduction using an array speaker by using a sound reproduction method in which a sound signal is generated and emitted from the array speaker. .

  In this case, depending on whether the front speaker including the subwoofer channel speaker is used or not used, a step of generating a sound case signal for emitting the sound signal of the front channel as a sound wave from the virtual speaker is required. Whether or not will be different.

  In addition, a step of generating a main signal in a computer mounted on an acoustic device using the array speaker system, a step of generating a sound case signal for emitting sound as a plane wave from the generated main signal, and an auxiliary signal And a step of generating a sound case signal for emitting sound as a plane wave from the generated auxiliary signal, and mixing the sound case signal generated using this program Then, by supplying each speaker of the array speaker system, a playback device similar to the playback device of the above-described embodiment can be realized.

  That is, the function of each block shown in FIGS. 1 and 14 can be realized by a program (software) installed in the audio device.

It is a block diagram for demonstrating the reproducing | regenerating apparatus with which one Embodiment of this invention was applied. It is a figure which shows the system | strain until the main signal SLm is produced | generated and the main signal SLm arrives at a listening area as a plane wave. It is a figure which shows the system | strain until it produces | generates auxiliary signal SLa and the auxiliary signal SLa arrives at a listening area as a plane wave. It is a figure for demonstrating the waveform obtained when the response in the vicinity of a listener's right and left ears is observed using a burst signal of 1 kHz. It is a figure which shows the system | strain until the main signal SRm is produced | generated and the main signal SRm arrives at a listening area as a plane wave. It is a figure which shows the system | strain until it produces | generates auxiliary signal SRa and the auxiliary signal SRa arrives at a listening area as a plane wave. It is a figure which shows the sound field in the virtual closed curved surface which does not contain a sound source. It is a figure which shows the integration formula of Kirchhoff. It is a figure which shows the system which reproduces the sound pressure and particle velocity of N point with M sound sources. It is a figure which shows the principle of expansion to the half space of Kirchhoff's integral formula. It is a figure which shows the specific example of the expansion to the half space of the integration formula of Kirchhoff. FIG. 2 is a block diagram showing a configuration of an audio data processing system 3 of the playback apparatus shown in FIG. 1 in which processing units are grouped for each audio channel. FIG. 10 is a block diagram for explaining another configuration example of the audio data processing system 3. FIG. 14 is a block diagram showing another configuration example of the audio data processing system 3 shown in FIG. 13 in more detail.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical disk reading part, 2 ... Demultiplexing circuit, 3 ... Audio | voice data processing system, 4 ... Video data processing system, 31 ... Audio | voice data decoder, 32 ... Time-axis adjustment circuit, 33W, 33F ... Amplifying circuit, SPW ... Sub Woofer channel speaker, SPL ... Left channel speaker, SPC ... Center channel speaker, SPR ... Right channel speaker, 34L, 34R ... Main signal generation circuit, 35L, 35R ... Auxiliary signal generation circuit, 36 (1), 36 (2), 36 (3), 36 (4) ... sound field signal generation circuit, 37 ... mixer, 38 ... n-channel amplifier circuit, SPAr ... array speaker system, 41 ... subtitle data decoder, 42 ... subtitle reproduction circuit, 43 ... video data decoder 44 ... Video reproduction circuit, 45 ... Superimpose circuit, 46 ... Video display device

Claims (7)

A front surround type sound device that reproduces a surround sound source having a rear channel that is a channel of a rear surround sound through a speaker group including a plurality of speakers arranged adjacent to only in front of a listener,
Based on the rear channel signal, a main signal generating means for generating a main signal that cancels the transfer characteristic from the speaker group to the listening area and convolves the transfer characteristic from the rear to the listening area;
Auxiliary signal generating means for forming an antiphase signal from the same signal as the main signal and generating an auxiliary signal at least delayed in phase of the antiphase signal;
An audio signal supplied to the loudspeaker group, which is a main signal for forming a sound signal for a main signal radiated as a plane wave from a direction opposite to the left and right to the listening area from the auxiliary signal. Sound signal generating means,
Auxiliary signal that is an audio signal of audio radiated from the group of speakers, and that forms a sound signal from the auxiliary signal for an auxiliary signal radiated as a plane wave from the opposite direction to the main signal toward the listening area. A sound apparatus comprising: a sound case signal generating means for use. The acoustic device according to claim 1,
Front channel processing means for forming, from each of the audio signals of the front channel other than the rear channel, an audio signal to be supplied to each of one or more front speakers other than the speaker group arranged in front of the listener An acoustic device comprising: The acoustic device according to claim 1,
An audio signal to be supplied to the speaker group, wherein a sound signal for the front channel that radiates each of the audio signals of the front channel other than the rear channel from the virtual speaker is an audio signal of the front channel. An acoustic apparatus comprising sound case signal generating means for a front channel audio signal formed from each. A surround surround sound reproduction method for reproducing a surround sound source having a rear channel which is a channel of a rear surround sound through a speaker group including a plurality of speakers arranged adjacent to only in front of a listener,
Based on the signal of the rear channel, a main signal generating step of generating a main signal that convolves the transfer characteristic from the rear to the listening area by canceling the transfer characteristic from the speaker group to the listening area;
An auxiliary signal generating step of forming an anti-phase signal from the same signal as the main signal and generating an auxiliary signal at least delayed in phase of the anti-phase signal;
An audio signal supplied to the loudspeaker group, which is a main signal for forming a sound signal for a main signal radiated as a plane wave from a direction opposite to the left and right to the listening area from the auxiliary signal. Sound signal generation process,
Auxiliary signal that is an audio signal of audio radiated from the group of speakers, and that forms a sound signal from the auxiliary signal for an auxiliary signal radiated as a plane wave from the opposite direction to the main signal toward the listening area. A sound reproduction method comprising: a sound signal generating step for generating sound. It is the sound reproduction method of Claim 4, Comprising:
A front channel processing step of forming, from each of the audio signals of the front channel other than the rear channel, an audio signal to be supplied to each of one or more front speakers other than the speaker group arranged in front of the listener; A sound reproduction method comprising: It is the sound reproduction method of Claim 4, Comprising:
An audio signal to be supplied to the speaker group, wherein a sound signal for the front channel that radiates each of the audio signals of the front channel other than the rear channel from the virtual speaker is an audio signal of the front channel. A sound reproduction method comprising a step of generating a sound signal for a front channel audio signal formed from each. A computer mounted on a front-surround sound device that reproduces a surround sound source having a rear channel, which is a channel of the rear surround sound, through a speaker group consisting of a plurality of speakers arranged adjacent to the front of the listener only. ,
Based on the signal of the rear channel, a main signal generating step for generating a main signal that cancels the transfer characteristic from the speaker group to the listening area and convolves the transfer characteristic from the rear to the listening area;
An auxiliary signal generation step of forming an anti-phase signal from the same signal as the main signal and generating an auxiliary signal at least delayed in phase of the anti-phase signal;
An audio signal supplied to the loudspeaker group, which is a main signal for forming a sound signal for a main signal radiated as a plane wave from a direction opposite to the left and right to the listening area from the auxiliary signal. A sound signal generation step;
Auxiliary signal that is an audio signal of audio radiated from the group of speakers, and that forms a sound signal from the auxiliary signal for an auxiliary signal radiated as a plane wave from the opposite direction to the main signal toward the listening area. A sound reproducing program for executing a sound signal generating step for sound.

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